1. Field of the Invention
The present invention relates in general to computers, and, more particularly, to an apparatus and method of effectively cooling multiple hard disk drives (HDDs) mounted on a HDD tray in a disk array storage system enclosure.
2. Description of the Prior Art
Hard disk drives (HDDs) are typically installed using HDD trays within an enclosure of a server computer system and/or a disk array storage system. FIG. 1 depicts an array 10 of HDDs 12 which are installed in a disk array storage system enclosure 14. In these systems, one HDD is commonly placed on a HDD tray. In the case of a single HDD placed on a HDD tray, no special technique is utilized to keep the HDD cool using forced air. In cases of multiple HDD installed in a system enclosure 14, multiple HDD trays are commonly placed in the front portion of the enclosure 14. Air inlet openings allow forced air to cool the HDDs in the system 14 as air travels from the front of the enclosure 14 to the rear of the enclosure 14.
Prior art enclosures 14 have inherent space limitations when used as previously described. A storage capacity ceiling is created which limits the ability to expand HDD storage capacity. As more HDD trays are added within the limited internal space of a system enclosure 14, the front of the enclosure 14 is filled and cannot accept additional HDDs. Manufacturers have resorted to placing multiple HDDs on a deep HDD tray in a tandem arrangement in order to achieve a more highly-dense installation of HDDs in the existing space. FIG. 2 depicts a high-density assembled disk array storage system 16. System 16 includes a set of three HDDs 12 which are arranged in tandem in a deep HDD tray 18. Trays 18 are inserted in a stacked arrangement into enclosure 14.
Without increasing the surface area of the air inlet openings of each tray 18, the high-density tandem installation of HDDs 12 in a storage system 16 as shown in FIG. 2 results in poor effectiveness in cooling the HDDs 12. HDDs 12 are ineffectively cooled because an insufficient airflow volume results from increased internal airflow impedance. Having a powerful air fan or blower may help to solve this thermal condition. However, other problems can be created as a result, involving aspects of product cost, electrical power supply, acoustic performance and limited internal space. Using a system incorporating a front-to-back airflow cooling method, the front HDDs 12 exhaust pre-heated air toward the rear HDDs 12 in enclosure 14. It is difficult to keep the rear HDDs 12 cooled effectively.
Thus, a need exists for an apparatus and method to effectively and efficiently cool a series of densely arranged HDDs in a storage enclosure without the use of a large fan or similar device. The apparatus and method should take cost and efficiency considerations into account.